Yes it is true. These organisations play their role in two ways:
(i) One way of influencing the decisions in a democracy is direct participation in competitive politics. This is done by creating parties, contesting elections and forming governments.
(ii) There are many indirect ways in which people can get government to listen to their demands or their points of view. They could do so by forming an organisation and undertaking activities to promote their interest or their viewpoint. These are called interest groups or pressure groups.
Sometimes people decide to act together without forming organisations.